These ripples are called gravitational waves and they emanate
from calamitous cosmic events like when a star explodes or when
two black holes bump into each other.

Albert Einstein first predicted their existence 100 years ago,
and physicists have been hunting for them ever since. Now, some
physicists are saying they're hearing whispers that
scientists at the Laser Interferometer
Gravitational-Wave Observatory (LIGO) have finally detected the waves out
in space.

LIGO has not confirmed the rumor is true, and many have their
doubts about its veracity since a false alarm has
happened before.

But here's how we'd know if LIGO really detected gravitational
waves or not, according to an animation
created by the lab.

How to detect gravitational waves

LIGO is a huge L-shaped detector that's been hunting
gravitational waves since 2002. It relies on
a laser to search for them.

The instrument shoots out a laser beam which gets split in two
and sent down two 2.5-mile long tubes.

The beams both bounce off mirrors and converge back near the
beam splitter. The light waves return at equal length, and line
up in such a way that they cancel each other out.

As a result, the light detector part of the instrument doesn't
see any light.

But should a gravitational wave come through, it would warp
spacetime, and actually make one tube longer and the other
shorter. This rhythmic stretching and squeezing would continue
until the wave passes.

When this kind of interference happens, the two waves aren't
equal lengths when they return, so they don't line up as neatly
and no longer cancel each other out.

That means the detector would actually record some flashes
of light. So a physicist measuring those changes
in brightness would actually be measuring and observing
gravitational waves.

LIGO scientists have told reporters that there is a lot of data
to comb through and that they'll announce a discovery if and when
they detect these signals.

They've made no announcement yet, but at least we know what
they're searching for.